<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>登录界面</h1>
<script>
    if(location.search=='?cause=nologin'){
        window.setTimeout(()=>{
            alert("请先登录系统");
        },200);
    }
</script>
</body>
</html>